1. Field of the Invention
The present invention relates to a method for merging plural meshes whose density differs from each other.
2. Description of the Related Art
FIGS. 7A and 7B show an example of a polygon image 80 obtained by the conventional method for merging meshes.
Conventionally, there are proposed methods for generating the entire three-dimensional shape data of a certain object based on a plurality of fragmentary three-dimensional shape data of the object.
According to a method disclosed in Related Publication 1 (Japanese unexamined patent publication No. 8-293042), for example, three-dimensional shape data of an object are input from various directions to bring three-dimensional shape data into alignment with other three-dimensional shape data. A cutting plane is set for each boundary between neighboring three-dimensional shape data to determine range shape data divided by the cutting plane. Then, for each of the cutting planes, data of areas sandwiching the cutting plane of range shape data are represented by two-dimensional coordinates, Delaunay triangulation is used to generate triangle patch data on the areas, and plural three-dimensional shape data are integrated (merged) with each other.
According to a method disclosed in Related Publication 2 (“Zippered Polygon Meshes from Range Images”, Greg Turk and Marc Levoy, Computer Science Department Stanford University), polygons overlapping at a boundary between neighboring meshes (polygon meshes) are removed from the meshes. Then, polygons intersecting at the boundary are detected to create intersections, so that polygons are reconstructed.
As shown in FIG. 7A, there are cases where neighboring two meshes 81 and 82 to be merged have polygon density (resolution in displaying) differing from each other.
In the conventional methods, merging is performed without regard to differences in resolution. Accordingly, when the conventional methods are adopted to merge the mesh 81 with the mesh 82 whose resolution substantially differs from that of the mesh 81, large changes occur in resolution at a seam (a boundary) between the meshes, as a polygon image 80 shown in FIG. 7B. Further, a polygon having an undesirable shape may be generated, such as a polygon that is excessively large in edge length, or a polygon that is extremely small in minimum interior angle. In such a case, a polygon image obtained by merging meshes appears unnatural.